Nitrogen oxides (NOx) are generated from a moving source such as a ship or an automobile or a fixed source such as a power station or an incinerator. Since these nitrogen oxides have been pointed out as one of the main causes of polluting air by forming acid rain and smog, various methods for removing nitrogen oxides have been proposed.
Among them, examples of a method for removing nitrogen oxides emitted from fixed sources include a selective catalytic reduction for denitrifying nitrogen oxides by applying a titania-based catalyst composed of a support including titanium oxide and an active catalyst component including vanadium oxide in the presence of ammonia as a reducing agent.